Press brake ram leveling

ABSTRACT

A press brake having a ram leveling adjustment in its ram advancing means is disclosed. Adjustment can be made even though tooling is secured to the bed and ram. In a preferred embodiment, the mechanical portion of the ram advancing means includes substantially parallel, linked bell cranks, each having a pivot, and at least one of the pivots inludes an eccentric pivot pin which can be rotated to a desired position for ram leveling adjustment. Preferably the orientation of the eccentric pivot pin is adjusted, and secured after adjustment, by means of a manually operable gear system which is self-locking with respect to forces applied at the pivot pin.

United States Patent [191 Kirincic et al.-

[ Oct. 9, 1973 PRESS BRAKE RAM .LEVELING [73] Assignee: Dreis & KrumpManufacturing (30.,

Chicago, Ill.

[22] Filed: Apr. 17, 1972 [21] Appl. No.: 244,577

2,353,388 7/1944 Cannon 100/258 A Primary Examiner--Richard J. HerbstAttorney-John D. Dewey et a1.

[57] ABSTRACT A press brake having a ram leveling adjustment in its ramadvancing means is disclosed. Adjustment can be made even though toolingis secured to the bed and ram. In a preferred embodiment, the mechanicalportion of the ram advancing means includes substantially parallel,linked bell cranks, each having a pivot, and at least one of the pivotsinludes an eccentric pivot pin which can be rotated to a desiredposition for ram leveling adjustment. Preferably the orientation of theeccentric pivot pin is adjusted, and secured after adjustment, by meansof a manually operable gear system which is self-locking with respect toforces applied at the pivot pin.

5 Claims, 6 Drawing Figures PATENTED um 9 ma SHEET 30! 3 1 PRESS BRAKERAM LEVELING This invention relates to the manufacture and use of pressbrakes, and specifically to leveling adjustment.

The modern press brake is regarded as a high powered production tool,and is considered to be a versatile machine. Many kinds of press workcan be accomplished quickly, easily and cheaply, with the use of toolswhich are readily available or which can be conveniently developed forspecial uses. The press brake can perform bending, forming, blanking,notching, shearing, rubber forming, multiple piercing, and otheroperations.

Because of the high performance characteristics which are required inthe press brake construction, press brakes are expensive. In recentyears there has been greater emphasis toward simplification, and otherdesign development which help reduce the cost of manufacture of pressbrakes, and increase their versatility. It is well known that pressbrakes generally include a stationary bed and a reciprocable ram, eachof which are adapted to receive the necessary tooling for theperformance of the desired operations. It is also well known that it ishighly desirable to provide some means of leveling the working faces ofthe tools, and of making and securing fine adjustments in the relativeangular orientation of the tools. For example, press brakes can be usedin the manufacture of elongated articles such as tapered metal lightpoles, and it is highly desirable to be able to make and secureadjustments in the order of thousandths of inches in the relativespacing of one or both ends of the tooling.

It is an object of the present invention to provide a highly versatilepress brake having means for leveling adjustment in the mechanicalportion of the ram advancing means. It is a further object of theinvention to provide such a leveling adjustment by which the relativespacing of one or both ends of the tooling can be reliably andaccurately changed by an operator, which adjustment is then reliably,and accurately secured and maintained during the operation of the pressbrake.

It is a further object of a preferred embodiment of the presentinvention to provide a press brake having leveling means associated withthe ram, which leveling means can be manually controlled by an operatorthrough a high mechanical advantage system, with which extremely fineadjustment in the leveling can be made as the result of relatively largeadjustments by the operator in the adjustment control means of thesystem.

It is another object of the present invention to provide press brakeleveling means which are characterized by simplicity of design, and arefurthermore operable without disturbing the attachment of tooling whichis secured to the bed and/or ram.

These and other objects which will be apparent hereinafter are achievedin accordance with the present invention which is described generally,and in connection with a particularly preferred embodiment, with'the aidof the accompanying drawings in which:

FIG. 1 is a perspective view of an improved press brake in accordancewith the present invention;

FIG. 2 is a highly simplified elevational illustration of hydraulic andmechanical elements involved in advancing and returning the ram of thepress brake shown in FIG. 1;

FIG. 3 is an enlarged fragmentary front view of the upper right handportion of the press brake illustrated in FIG. 1;

FIG. 4 is a cross sectional view taken approximately along the line 4-4of FIG. 3;

FIG. 5 is an enlarged cross sectional view taken approximately along theline 5-5 of FIG. 4; and

FIG. 6 is an enlarged fragmentary partially cut-away front view of theadjustment gear box shown in the upper righthand portion of FIG. 1.

Referring now to the figures, a press brake is generally indicated at10. Brake 10 comprises a frame, generally indicated at 12, a stationarybed or lower blade, generally indicated at 14, a ram or upper blade,generally indicated at 16 and hydraulic-mechanical power means,generally indicated at 18, for advancing and returning ram 16.

The main press brake frame 12 is fabricated of steel plate, and pressbrake frames are conventionally designed for minimum accepteddeflection. Frame 12 is fabricated by welding steel plates includingside plates 20, and cross members 22. Bed 14 can be considered ascontributing substantially to the rigidity since lateral portions 24 ofbed 14 are also welded to side plates 20. Side plates 20 rest on feetportions 26. The nature of the conventional platens and conventionalupper'or lower die sets which can be used with press brake 10 will notbe described herein since these pieces are conventional and are not partof the novel aspects of the present invention.

The hydraulic-mechanical power train means 18 for advancing andreturning ram 16 are illustrated in FIG.

Referring specifically to FIG. 2, double acting cylinder 30 is pivotallysupported on horizontal hinge pin 32 which is carried between framecross members 22, 22. Cylinder 30 is powered through hydraulic line 34during advance of ram 16, and through hydraulic line 36 during return ofram 16. Hydraulic cylinder 30 advances and retracts cylinder rod 38which, in turn, is pivotally attached to, and drives, master lever 40 bymeans of connection thereto through clevis 42 and horizontal pin 44.Master lever 40 is pivotally supported on master lever support pin 46which is carried between frame cross members 22. Along a line passingbetween the centers of pins 44, and 46 another pivot pin 48 pivotallyconnects tie bar 50 to master lever 40.

The other end 52 of tie bar 50 is pivotally connected to bell crank 54through pivot pin 56. Bell crank 54 is supported pivotally by pivot pin58 which is supported between cross members 22. Vertical links '60, and62 are pivotally connected with master lever 40 and bell crank 54,respectively, by pivot pins 64, 66 respectively. Links 60, 62 arepivotally connected with ram 16 near respective ends thereof throughpivot pins 68, and 70 respectively.

Master lever 40, and bell crank 56 are both levers, each having twofunctioning lever arms forming an angle, each lever arm having itsfulcrum at the apex of the angle. Thus, master lever 40 also fallswithin the definition of a bell crank. Both the master lever 40 and bellcrank 56 have corresponding vertical and horizontal lever arms. Pivots46, and 58, respectively, serve as the apex of the respective anglesformed by the respective pair of horizontal and vertical lever arms. Thelever arms are not separate structures but are part of bell crank 54 andmaster lever 40. They include corresponding vertical lever arms betweenpivots 56, 58 on bell crank 54 and between pivots 46 and 48 on masterlever 40. The other corresponding lever arms can be considered to be theimaginary horizontal lever arms between pivot 56 and 66 in bell crank54, and between pivots 46 and 64 in master lever 40. The respectivecorresponding functional lever arms are identical in length and aresubstantially parallel in the preferred illustrated embodiment, and theangle therebetween is substantially 90.

Thus, the respective lever-functioning portions of master lever 40 andbell crank 54 are substantially identical in length, and thecorresponding lever arms are substantially parallel. Hence lever 40 andbell crank 54 provide parallel bell cranks as part of the ram advancingmeans.

Comparing FIGS. 1 and 2 it will be appreciated that pivot pins 32, 46,and 58 are supported between cross members 22, 22. The ends of pivotpins 32, 58 can be seen on the face of front cross member 22. Pivot pin32 is seen to be supported in the upward frame extensions 72, 72 whichare integral with respective frame cross members 22, 22. Pivot pin 68can be seen in the middle left-hand portion of cross member 22 in theview of FIG. 1.

However, pivot pin 46, around which the master lever 40 pivots, is notvisible in the view of FIG. 1 since it terminates within gear box 74. Itwill be appreciated from the following description that pivot pin 46 isan important part of the ram tilt adjustment mechanism in accordancewith the present invention.

Referring now to FIG. 3 a portion of cover 76 at the lower extreme ofgear box 74 is removed for the purpose of clarity of illustration. Frontend of pivot pin 46 is visible in the view of FIG. 3 as is worm wheelgear 82 which is fixed to pivot pin 46. Worm gear 84 meshes with wormwheel 82, and is fixed with respect to shaft 86. Worm gear 84 and shaft86 are rotatably supported by thrust bearings 88 at both sides of gearbox 74.

Shaft 86 extends out of gear box 74 to a point beyond cross member 22.Handle 90 is rotatably attached to crank lever 92, which is fixed withrespect to the end of shaft 86. Shaft 86 passes through bracket 94 whichis bolted to cross member 22, and thumb screw 96 can be threaded throughan opening in bracket 94 to lock shaft 86 against inadvertent rotationdue to accidental bumping of handle 90 on crank lever 92.

Referring now to FIG. 4, pivot pin 46 is rotatably carried in bearings100 at both front and rear plates 22. Bearings 100 pass through openingsin plate 22-and reinforcing collars 102, 102 which are welded to theinner side of both cross members 22, 22. Front portion 104 and rearportion 106 within bearings 100 are concentric portions of pivot pin 46.Center portion 108 is eccentric with respect to the center of portion104, 106 and is circular. Eccentric center portion 108 is rotatablypositioned within bushing 110 which extends through an appropriateopening in master lever 40 and front and rear collars 112 which arewelded to master lever 40 to provide reinforcement thereof. Theeccentricity shown in FIG. 4 is exaggerated greatly for the purpose ofmore clearly illustrating the principles and operation of the presentinvention. In a preferred embodiment, the eccentricity would be suchthat a oneeighth inch throw would be achieved. From FIG. 4 it is alsoapparent that reinforcement collars 116 and 118 are welded to masterlever 40 both at the front and rear face thereof to providereinforcement at the openings for pins 44, 48, respectively.

It is an important aspect of a preferred embodiment of the presentinvention that the gear ratio of gearing system 81, by which the angularorientation of adjustment of pivot pin 46 can be changed and setmanually,

for example, by rotation of crank lever 92, to be high enough that thesystem is self-locking with respect to forces applied to it through pin46. When, in accordance with a preferred embodiment of this invention,which is specifically illustrated in the drawings, a worm gear 84 isused in the gearing system 81, the lead angle of the worm gear must besufficiently steep to permit pin 46 to be rotated by rotation of crank92, and yet be at an angle which will not permit it to be driven by wormwheel gear 82. Naturally, the exact range of usable lead angles on sucha worm gear will depend on the particular dimensions of the elementscoacting therewith, on the amounts of lubrication provided, on theamounts of vibration present, and on other variables. We have found thatworm gears having thread lead angles in the neighborhood of nine degreesare eminently satisfactory for use in accordance with this invention.Nonetheless, it is highly desirable to provide means for locking crankshaft 86 against inadvertent rotation of crank caused by operatorbumping, vibration, etc., and the illustrated embodiment, thumb screw 96is provided for this purpose.

The specific embodiment described herein is provided for illustration,and the invention is not to be limited thereby. It will be apparent tothose skilled in the art that many changes and modifications can be madewithout departing from the spirit or scope of the present invention.Consequently the scope of the invention is not to be limited by theillustrations provided in the disclosure, but only by the claimsappended hereto.

We claim:

1. A press brake comprising hydraulic-mechanical power means foradvancing and returning a ram, said power means including a plurality ofbell cranks pivotally supported by a frame, at least one of said bellcranks being pivotally supported on an eccentric portion of an operatorrotatable shaft rotatably supported on said frame.

2. The press brake of claim 1 wherein said shaft is attached to gearmeans for rotating said shaft, said gear means being self-locking withrespect to forces applied to it from said shaft.

3. The press brake of claim 1 in which said shaft has worm gear meansoperably connected therewith, said worm gear means including a wormwheel gear fixed with respect to said shaft, and including a worm gearoperably engaging said worm wheel gear, and handle means for rotatingsaid worm gear.

4. The press brake of claim 3 in which said shaft has indicator meansfixed thereto to correspond to predetermined position adjustment of saidram.

5. A press brake comprising a rigid frame, a bed, a ram, and drivingmeans for advancing and returning the ram, limit means for limiting thelength of travel of the ram while advancing and returning, said drivingmeans comprising double acting hydraulic cylinder means for extendingand retracting a piston rod, said ram being supported at a plurality ofpoints by respective lengths pivotally attached to respective firstlevers of respective bell cranks, said bell cranks being pivotallyconnected to said frame on respective pivot shafts, said bell ton rod,at least one of said bell crank pivot shafts having an eccentric portionsupporting the respective bell crank, said shaft having gearing meansfor rotation of said eccentric portion, said gearing means beingselflocking with respect to forces applied to it from said eccentricportion.

1. A press brake comprising hydraulic-mechanical power means foradvancing and returning a ram, said power means including a plurality ofbell cranks pivotally supported by a frame, at least one of said bellcranks being pivotally supported on an eccentric portion of an operatorrotatable shaft rotatably supported on said frame.
 2. The press brake ofclaim 1 wherein said shaft is attached to gear means for rotating saidshaft, said gear means being self-locking with respect to forces appliedto it from said shaft.
 3. The press brake of claim 1 in which said shafthas worm gear means operably connected therewith, said worm gear meansincluding a worm wheel gear fixed with respect to said shaft, andincluding a worm gear operably engaging said worm wheel gear, and handlemeans for rotating said worm gear.
 4. The press brake of claim 3 inwhich said shaft has indicator means fixed thereto to correspond topredetermined position adjustment of said ram.
 5. A press brakecomprising a rigid frame, a bed, a ram, and driving means for advancingand returning the ram, limit means for limiting the length of travel ofthe ram while advancing and returning, said driving means comprisingdouble acting hydraulic cylinder means for extending and retracting apiston rod, said ram being supported at a plurality of points byrespective lengths pivotally attached to respective first levers ofrespective bell cranks, said bell cranks being pivotally connected tosaid frame on respective pivot shafts, said bell cranks being connectedto each other by connecting rod means at second lever arms of said bellcrank, said first lever arms being substantially identical, and each ofsaid second lever arms being substantially identical, and the anglebetween respective first and second lever arms being identical, one ofsaid bell cranks including an extending arm portion pivotally secured tosaid piston rod, at least one of said bell crank pivot shafts having aneccentric portion supporting the respective bell crank, said shafthaving gearing means for rotation of said eccentric portion, saidgearing means being self-locking with respect to forces applied to itfrom said eccentric portion.